Title Page
Abstract
Contents
Chapter 1. Introduction 15
1.1. Study Background 15
1.2. Selective catalytic reduction of NOₓ with NH₃ 19
1.3. Purpose of Research 21
Chapter 2. Enhanced SO₂ resistance of V₂O₅/WO₃-TiO₂ catalyst physically mixed with alumina for the selective catalytic reduction of NOₓ with NH₃ 23
2.1. Introduction 23
2.2. Experimental 25
2.2.1. Catalyst preparation 25
2.2.2. Reaction condition 26
2.2.3. Characterizations 27
2.3. Results and discussions 29
2.3.1. SO₂ aging tests over the physically mixed vanadia catalysts with alumina 29
2.3.2. Sulfur distribution in the physically mixed vanadia catalysts with alumina 36
2.3.3. ABS migration through physical contact between vanadia and alumina 47
2.3.4. Sulfur resistance depending on the calcination temperature of physically mixed alumina 58
2.3.5. Regeneration test of the alumina mixture catalyst 65
Chapter 3. Tailoring the Mechanochemical Interaction Between Vanadium Oxides and Zeolite for Sulfur-Resistant DeNOₓ Catalysts 73
3.1. Introduction 73
3.2. Experimental 75
3.2.1. Catalyst preparation 75
3.2.2. Reaction condition 76
3.2.3. Characterizations 77
3.3. Results and discussions 78
3.3.1. Effect of mixing Al-rich zeolite with the VWTi catalyst 78
3.3.2. Grinding induced Al redistribution in mechanical mixtures 85
3.3.3. Regulating Al diffusion using a carbon barrier surrounding zeolite 98
Chapter 4. Understanding the ball milling effects over ball milled V₂O₅/WO₃-TiO₂ with zeolite Y for selective catalytic reduction of NOₓ with NH₃. 116
4.1. Introduction 116
4.2. Experimental 118
4.2.1. Catalyst preparation 118
4.2.2. Reaction condition 119
4.2.3. Characterizations 120
4.3. Results and discussion 121
4.3.1. Catalytic activity tests over the ball milled 5 wt.% V₂O₅/WO₃-TiO₂ catalyst with zeolite Y(Si:Al₂=12) 121
4.3.2. Optimizing the ball milling process of 5 wt.% V₂O₅/WO₃-TiO₂ catalyst with zeolite Y 141
Chapter 5. Conclusions and summary 151
Bibliography 154
초록 160
Table 2-1. Elemental analysis on 5VWTi + Al mixture catalysts after SO₂ aging under 30 ppm of a SO₂-containing flow at 220 ℃ for 22 h. 46
Table 2-2. Surface areas and pore size distributions of the alumina calcined at different temperatures, 600 ℃, 900 ℃, and 1000 ℃. 64
Table 2-3. Elemental analysis on 5VWTi + 900cal catalyst Al after each regeneration step at 350 ℃ for 2 h. 70
Table 2-4. Deactivation rates of 5VWTi + 900cal Al catalyst after each regeneration step at 350 ℃ for 2 h and 5VWTi + 6 wt.% ABS/Al after SO₂... 71
Table 3-1. Elemental analysis (CNHS) of the carbon-coated Y-zeolite with Si: Al₂=5.1 (OTSY-5.1) before and after calcination at 350 ℃ and 500 ℃... 105
Table 4-1. Surface areas and pore size distributions of VWTi + Y12 catalyst synthesized by hand mixing and ball milling. 128
Fig. 1-1. Major Air pollutants and schematic of fine particulate matters. 17
Fig. 1-2. NOₓ Emission standards of mobile sources on worldwide. 18
Fig. 1-3. The scheme of selective catalytic reduction with NH₃. 20
Fig. 2-1. SCR catalytic activity profiles of the 5VWTi and 5VWTi + 900cal Al catalysts. 30
Fig. 2-2. NOₓ conversion profile of 5VWTi, 900cal Al and 5VWTi + 900cal Al catalysts during SO₂ aging at 220 ℃ for 22 h. 31
Fig. 2-3. Deactivation rates of the physically mixed vanadia catalysts with calcined alumina at different temperatures (600 ℃, 900 ℃, and 1000 ℃)... 33
Fig. 2-4. NOₓ conversion profiles of the physically mixed vanadia catalysts with calcined alumina at different temperatures (600 ℃ and 1000 ℃) at... 34
Fig. 2-5. (a) NOₓ conversion profiles of the 5VWTi and 5VWTi + Al catalysts during SO₂ aging at 220 ℃ and (b) deactivation rates of the... 35
Fig. 2-6. (a) Corrected transmission electron microscope (Cs-TEM) image and (b) line energy dispersive X-ray spectroscopy (line-EDS) scans of... 38
Fig. 2-7. (a, c, and e) Cs-TEM images and (b, d, and f) line-EDS scans of 5VWTi + 600cal Al, 5VWTi + 900cal Al, and 5VWTi + 1000cal Al... 39
Fig. 2-8. TPD-MS analyses of the SO₂ aged 5VWTi and the SO₂ aged alumina mixture catalysts (SO₂ aged under 30 ppm of a SO₂-containing flow... 42
Fig. 2-9. Temperature-programmed desorption-mass spectroscopy (TPD-MS) analyses of (a) the 2 wt.% of ABS pre-impregnated 5VWTi and (b) the... 43
Fig. 2-10. Comparison of the NOₓ conversion of physically contacted 5VWTi + 900cal Al and loosely contacted 5VWTi + 900cal Al (5VWTi +... 49
Fig. 2-11. (a) Cs-TEM image and (b) line-EDS scans of loosely contacted 5VWTi + 900cal Al-L catalyst after sulfur aging at 220 ℃ for 22 h. 52
Fig. 2-12. TPD-MS analysis of the SO₂ aged 900cal alumina (30 ppm of SO₂-containing flow at 220 ℃ for 22 h) under 100 mL/min of a N₂ flow at a... 53
Fig. 2-13. NOₓ conversion profiles of ABS pre-impregnated 5VWTi + 900cal Al and 5VWTi + 900cal Al-L catalysts at a heating rate of 1 ℃/min... 56
Fig. 2-14. Schematic of ABS migration through physical contact in 5VWTi... 57
Fig. 2-15. Catalytic activities of the 2 wt.% ABS/5VWTi and 2 wt.% ABS/5VWTi + calcined alumina catalysts from 100 ℃ to 220 ℃ at a... 61
Fig. 2-16. (a) NH₃ temperature-programmed desorption (NH₃-TPD) profiles, (b) N₂ adsorption-desorption isotherms, (c) X-ray diffraction... 63
Fig. 2-17. (a) Regeneration tests and (b) deactivation rates of the 5VWTi and 5VWTi + 900cal Al catalysts after three cycles of SO₂ aging and... 69
Fig. 2-18. Deactivation rates of the 5VWTi, and 5VWTi + 6wt.% ABS/Al catalysts (6 wt.% of ABS pre-impregnated on 900cal Al) in comparison with... 72
Fig. 3-1. HR-TEM images of the mechanical mixture of VWTi catalyst and Y-zeolite. VWTi-to-Y-zeolite ratio was fixed to 2:1 with respect to mass. 80
Fig. 3-2. NH₃-SCR activities at 220 ℃ during simulated deactivation for 22 h via the formation of ABS in the VWTi + zeolite mixed catalysts. 81
Fig. 3-3. The size of the Y-zeolite with different Si:Al₂ ratio was analyzed using dynamic light scattering. 82
Fig. 3-4. (a) Steady-state NOₓ conversion as a function of temperature during the standard NH₃-SCR reaction. VWTi-to-Y-zeolite ratio was fixed... 84
Fig. 3-5. (a) Solid-state ²⁹Si, (b) ²⁷Al, aⁿd (c) ⁵¹V NMR spectra of the mixed VWTi + Y-5.1 catalyst without grinding and after mechanical grinding. 87
Fig. 3-6. FTIR spectra of the mixed VWTi+Y-5.1 catalyst without grinding and after mechanical grinding. 88
Fig. 3-7. NH₃-TPD results over the Y-zeolite without grinding and after mechanical grinding. 90
Fig. 3-8. TEM image and EDS line scanning spectra for the mechanical mixtures of the VWTi + Y-12 and VWTi + Y-5.1 catalyst after grinding. 93
Fig. 3-9. (a) H₂-TPR results comparing the effect of mechanical grinding on the mixed VWTi + Y-5.1 and VWTi + Y-12 catalysts. (b) H₂-TPR results for... 94
Fig. 3-10. Kinetic analysis of the VWTi and the mixed catalysts under dry and wet reaction conditions. 96
Fig. 3-11. Kinetic analysis over the VWTi catalysts with various V₂O₅ loadings from 1 to 7 wt.%. 97
Fig. 3-12. Schematic of the grinding method using a protective carbon layer. 99
Fig. 3-13. (a) Scheme of organosilane (octadecyltrichlorosilnae, OTS) coating on the external surface of Y-zeolite. (b) Water droplet on the zeolite... 100
Fig. 3-14. FT-IR spectra for HY zeolite, OTS-Y zeolite, OTS-Y zeolite-350cal, and OTS-Y zeolite-500cal sample. 101
Fig. 3-15. Temperature programmed oxidation to 900 ℃ at a ramping rate of 10 ℃/min for OTS-Y-5.1 zeolite under 10% O₂/N₂(blue). The signals of... 102
Fig. 3-16. (a) ⁵¹V solid-state NMR spectra and (b) H₂-TPR results for VWTi + OTSY-5.1 catalyst. 106
Fig. 3-17. Steady-state NOₓ conversions as a function of temperature during the standard NH₃-SCR reaction for the VWTi + OTSY-5.1 catalyst... 107
Fig. 3-18. (a) NOₓ conversion in the NH₃-SCR reaction at 220 °C during accelerated deactivation for 44 h by forming ABS on the catalysts. (b)... 110
Fig. 3-19. NOₓ conversions comparison of OTS-Y-5.1 and starch-Y-5.1 zeolite composite material at 220 ℃ during simulated deactivation for 22 h. 112
Fig. 4-1. Catalytic activity of physically mixed V₂O₅ /WO₃-TiO₂ catalyst with zeolite Y12 and ball milled V₂O₅/WO₃-TiO₂ catalyst with zeolite Y12... 123
Fig. 4-2. (a) NOₓ conversion profiles of the VWTi and VWTi + Y12 B.M. catalysts with different frequency during SO₂ aging at 220 ℃ and (b)... 125
Fig. 4-3. X-ray diffraction (XRD) results of ball milled V₂O₅/WO₃-TiO₂ catalyst with zeolite Y12 with different frequency. 127
Fig. 4-4. H 2-TPR results of VWTi + Y12-B.M. catalysts with (a) different frequency and (b) time. 131
Fig. 4-5. (a) Corrected transmission electron microscope (Cs-TEM) image and (b) line energy dispersive X-ray spectroscopy (line-EDS) scans of... 132
Fig. 4-6. SEM images of (a) VWTi, (b) VWTi 10 Hz 10min B.M., (c) VWTi 20 Hz 10min B.M., and (d) VWTi 30 Hz 10min B.M. catalysts. 133
Fig. 4-7. SEM images of (a) zeolite Y12 (b) zeolite Y12 10 Hz 10min B.M., (c) zeolite Y12 20 Hz 10min B.M., and (d) zeolite Y12 30 Hz 10min B.M. catalysts. 134
Fig. 4-8. NH 3-temperature programmed desorption profiles of VWTi + Y 12 hand mixing and VWTi + Y12 B.M. catalysts. 137
Fig. 4-9. Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) of (a) VWTi + Y12-hand mixing, (b) VWTi+ Y12-10 Hz 10... 138
Fig. 4-10. Ratio of NH₃ adsorbed onto Bronsted acid sites over that onto Lewis acid sites (B/L Ratio) under NO+O₂ flow after NH₃ adsorption. 139
Fig. 4-11. Raman spectra of ball milled VWTi catalysts. 140
Fig. 4-12. Catalytic activity of ball milled V₂O₅/WO₃-TiO₂ catalyst with zeolite Y12 without(w/o) grinding ball. 143
Fig. 4-13. (a) NOₓ conversion profiles of the VWTi + Y12 B.M. catalysts without grinding ball during SO₂ aging at 220 ℃ and (b) deactivation rates... 144
Fig. 4-14. H₂-TPR results of VWTi + Y12-B.M. catalysts with and without grinding ball. 145
Fig. 4-15. XRD results of ball milled VWTi + Y512 with and without grinding ball. 146
Fig. 4-16. (a) Corrected transmission electron microscope (Cs-TEM) image and (b) line energy dispersive X-ray spectroscopy (line-EDS) scans of... 147
Fig. 4-17. Catalytic activity of ball milled V₂O₅/WO₃-TiO₂ catalyst with zeolite Y12 with different ball milling volume and ball size. 149
Fig. 4-18. H₂-TPR results of VWTi + Y12-B.M. catalysts with different ball milling volume and ball size. 150